Networking Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing networking and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

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  • N

    network interface unit (NIU or Network Interface Device)

    A network interface unit (NIU) (sometimes called a network interface device) is a device that serves as a common interfacefor various other devices within a local area network (LAN), or as an interface to allow networked computers to connect to an outside network.

  • Network layer

    Located at Layer 3 of the Open Systems Interconnection (OSI) communications model, the primary function of the network layer is to move data into and through other networks.

  • network management system

    A network management system (NMS) is an application or set of applications that lets network engineers manage a network's independent components inside a bigger network management framework and performs several key functions.

  • network monitoring

    Network monitoring is the practice of consistently overseeing a computer network for any failures or deficiencies to ensure continued network performance.

  • network node

    A network node is an endpoint or redistribution connection point for data transmissions on a communications network that can process or forward transmissions to other nodes.

  • network operating system (NOS)

    A network operating system (NOS) is a computer operating system (OS) that is designed primarily to support workstations, personal computers and, in some instances, older terminals that are connected on a local area network (LAN).

  • network operations center (NOC)

    A network operations center (NOC) is a centralized place from which enterprise information technology (IT) administrators -- either internal or third party -- supervise, monitor and maintain a telecommunications network.

  • network orchestration

    Network orchestration is a policy-driven approach to network automation that coordinates the hardware and software components a software application or service requires to run.

  • network packet

    A network packet is a small amount of data sent over Transmission Control Protocol/Internet Protocol (TCP/IP) networks.

  • network performance monitoring

    Network performance monitoring is a process of measuring and monitoring the quality of service of a network to understand if it is properly operating.

  • network perimeter

    A network perimeter is the boundary between the private and locally managed-and-owned side of a network and the public and usually provider-managed side of a network.

  • network protocol

    A network protocol is a set of established rules that dictate how to format, transmit and receive data so that computer network devices -- from servers and routers to endpoints -- can communicate, regardless of the differences in their underlying infrastructures, designs or standards.

  • network scanning

    Network scanning is a procedure for identifying active devices on a network by employing a feature or features in the network protocol to signal devices and await a response.

  • network security

    In information technology, network security is the act of maintaining the integrity of a computer network and the data within it.

  • network service provider (NSP)

    A network service provider (NSP) is a company that owns, operates and sells access to internet backbone infrastructure and services.

  • network switch

    A network switch is a hardware device that channels incoming data from multiple input ports to a specific output port that will take it toward its intended destination.

  • network tap

    A network tap is an external monitoring device that mirrors the traffic that passes between two network nodes. A tap (test access point) is a hardware device inserted at a specific point in the network to monitor data.

  • Network Time Protocol (NTP)

    Network Time Protocol (NTP) is a protocol used to synchronize computer clock times in a network.

  • network topology

    A network topology is the physical and logical arrangement of nodes and connections in a network.

  • network traffic

    Network traffic, sometimes referred to as data traffic, is the amount of data which moves across a network during any given time.

  • network visibility

    Network visibility is an awareness of the components and data within an enterprise computer network.

  • Networking (computer)

    Networking, also known as computer networking, is the practice of transporting and exchanging data between nodes over a shared medium in an information system.

  • Next Hop Resolution Protocol (NHRP)

    In a computer network, the Next Hop Resolution Protocol (NHRP) is a protocol or method that can be used so that a computer sending data to another computer can learn the most direct route (the fewest number of hops) to the receiving computer.

  • NFV MANO (network functions virtualization management and orchestration)

    NFV MANO (network functions virtualization management and orchestration), also called MANO, is an architectural framework for managing and orchestrating virtualized network functions (VNFs) and other software components.

  • NFVi (network functions virtualization infrastructure)

    NFVi (network functions virtualization infrastructure) encompasses all of the networking hardware and software needed to support and connect virtual network functions in carrier networks.

  • NIS (Network Information System)

    NIS (Network Information System) is a network naming and administration system for smaller networks that was developed by Sun Microsystems.

  • nslookup

    nslookup is the name of a program that lets an Internet server administrator or any computer user enter a host name (for example, "whatis.com") and find out the corresponding IP address or domain name system (DNS) record.

  • NVGRE (Network Virtualization using Generic Routing Encapsulation)

    NVGRE (Network Virtualization using Generic Routing Encapsulation) is a network virtualization method that uses encapsulation to create large numbers of virtual LANs (VLANs) for subnets that can extend across dispersed data centers and Layers 2 and 3.

  • O

    OA&M (operations, administration, and management)

    OA&M (operations, administration, and management) is a general term used to describe the costs, tasks involved, or other aspects of operating, administering, and managing something such as a computer network.

  • OC-768

    OC-768 is currently the fastest synchronous optical network (SONET) standard rate for data transmission on optical fiber as part of the broadband ISDN (BISDN).

  • OF-Config (OpenFlow Configuration and Management Protocol)

    The OpenFlow Management and Configuration Protocol (OF-Config) is a protocol developed under the Open Networking Foundation used to manage physical and virtual switches in an OpenFlow environment.

  • OFDMA (orthogonal frequency-division multiple access)

    Orthogonal frequency-division multiple access (OFDMA) is a feature of Wi-Fi 6 (802.11ax) that allows access points to serve multiple clients at the same time.

  • one-armed router

    A one-armed router is a router that routes traffic between virtual local area networks (VLANs).

  • ONOS (Open Network Operating System)

    ONOS (Open Network Operating System) is an operating system (OS) designed for network service providers to help build carrier-grade software-defined networks architected for high scalability, availability and performance

  • open networking

    Open networking describes a network that uses open standards and commodity hardware.

  • OpenFlow controller

    An OpenFlow controller is an application that manages flow control in a software-defined networking (SDN) environment.

  • OpenFlow switch

    An OpenFlow switch is a software program or hardware device that forwards packets in a software-defined networking (SDN) environment.

  • OpenStack Neutron (formerly called Quantum)

    OpenStack Neutron is a cloud networking controller and a networking-as-a-service project within the OpenStack cloud computing initiative.

  • operational support system (OSS)

    An operational support system (OSS) is a set of programs that help a communications service provider monitor, control, analyze and manage a telephone or computer network.

  • Optical Carrier levels (OCx)

    The Synchronous Optical Network (SONET) includes a set of signal rate multiples for transmitting digital signals on optical fiber.

  • optical line terminal (OLT)

    An optical line terminal (OLT) is a device that is located at the service provider's central office and is the endpoint of a passive optical network (PON).

  • optical network (photonic network)

    An optical (photonic) network transmits information as optical rather than electronic signals: It uses light, not electrical currents, to convey data.

  • optoelectronics

    Optoelectronics is a branch of electronics that overlaps with physics.

  • optoisolator (optical coupler or optocoupler)

    An optoisolator (also known as an optical coupler, photocoupler, optocoupler) is a semiconductor device that transfers an electrical signal between isolated circuits using light.

  • orthogonal frequency-division multiplexing (OFDM)

    Orthogonal frequency-division multiplexing (OFDM) is a method of data transmission where a single information stream is split among several closely spaced narrowband subchannel frequencies instead of a single wideband channel frequency.

  • OSGi (Open Service Gateway Initiative)

    OSGi (Open Service Gateway Initiative) is Java framework for developing and deploying modular software programs and libraries.

  • OSI model (Open Systems Interconnection)

    OSI (Open Systems Interconnection) is a reference model for how applications communicate over a network.

  • OSPF (Open Shortest Path First)

    The OSPF router protocol is used to find the best path for packets as they pass through a set of connected networks. OSPF is one of several Interior Gateway Protocols that replaces the Routing Information Protocol (RIP), an older routing protocol that is installed in many of today's corporate networks.

  • over-the-top (OTT)

    Over-the-top (OTT) is networking lingo that describes the delivery of content, services or applications over the internet.

  • overlay network

    An overlay network is a telecommunications network that is built on top of another network and is supported by its infrastructure.

  • OVSDB (Open vSwitch Database Management Protocol)

    The Open vSwitch Database Management Protocol (OVSDB) is an OpenFlow configuration protocol that is designed to manage Open vSwitch implementations.

  • P

    packet filtering

    On the Internet, packet filtering is the process of passing or blocking packets at a network interface based on source and destination addresses, ports, or protocols.

  • packet loss

    Packet loss is when one or more transmitted data packets fail to arrive at their destination.

  • passive optical network (PON)

    A passive optical network (PON) is a system commonly used by telecommunications network providers that brings fiber optic cabling and signals all or most of the way to the end user.

  • patch panel

    A network patch panel is a mounted hardware unit containing ports used to interconnect and manage LAN cables as well as connect them to the internet and wide area networks.

  • PCS (personal communications service)

    PCS (personal communications service) is a wireless phone service similar to cellular telephone service but emphasizing personal service and extended mobility. (Continued...)

  • peer-to-peer (P2P)

    Peer-to-peer (P2P) is a decentralized communications model in which each party has the same capabilities and either party can initiate a communication session.

  • permanent virtual circuit (PVC)

    A permanent virtual circuit (PVC) is a software-defined logical connection in a network such as a frame relay network.

  • Personal Access Communications System (PACS)

    Personal Access Communications System (PACS) is a type of wireless telephone network compatible with telephone sets, answering machines, fax machines, and computers.

  • phase-locked loop (PLL)

    A phase-locked loop (PLL) is an electronic circuit with a voltage or voltage-driven oscillator that constantly adjusts to match the frequency of an input signal.

  • physical layer

    Located at the lowest layer of the Open Systems Interconnection (OSI) communications model, the physical layer's function is to transport data using electrical, mechanical or procedural interfaces.

  • ping

    A ping (Packet Internet or Inter-Network Groper) is a basic internet program that enables a user to test and verify if a particular destination Internet Protocol (IP) address exists and can accept requests in computer network administration.

  • ping sweep (ICMP sweep)

    A ping sweep (also known as an ICMP sweep) is a basic network scanning technique used to determine which of a range of IP addresses map to live hosts (computers).

  • Plain Old Telephone Service (POTS)

    Plain Old Telephone Service (POTS) refers to the traditional, analog voice transmission phone system implemented over physical copper wires (twisted pair).

  • point-of-presence (POP)

    On the Internet, a point-of-presence (POP) is an access point from one place to the rest of the Internet.

  • Point-to-Point Protocol over Ethernet (PPPoE)

    Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol that facilitates communication between network endpoints.

  • poison reverse

    In a computer network that uses the Routing Information Protocol (RIP) or other distance vector routing protocol, poison reverse is a loop avoidance process.

  • policy-based networking

    Policy-based networking is the management of a network so that various kinds of traffic - data, voice, and video - get the priority of availability and bandwidth needed to serve the network's users effectively.

  • port

    A port in computing has three main uses, each as a type of receptacle in networking, computer hardware and software.

  • port 80

    On a Web server or Hypertext Transfer Protocol daemon, port 80 is the port that the server "listens to" or expects to receive from a Web client, assuming that the default was taken when the server was configured or set up.

  • Port Address Translation (PAT)

    Port Address Translation (PAT), is an extension to network address translation (NAT) that permits multiple devices on a local area network (LAN) to be mapped to a single public IP address. The goal of PAT is to conserve IP addresses.

  • port mirroring (roving analysis port)

    Port mirroring is an approach to monitoring network traffic that involves forwarding a copy of each packet from one network switch port to another.

  • port number

    Port number is a way to identify a specific process to which an internet or other network message is to be forwarded when it arrives at a server.

  • Power over Ethernet (PoE)

    Power over Ethernet (PoE) is a technology for implementing wired Ethernet local area networks (LANs) that enables the electrical current necessary for operating each device to be carried by Ethernet data cables instead of standard electrical power cords and wiring.

  • POX

    POX is an open source development platform for Python-based software-defined networking (SDN) control applications, such as OpenFlow SDN controllers.

  • PPP (Point-to-Point Protocol)

    PPP (Point-to-Point Protocol) is a standard used to establish a direct connection between two network nodes that enables the transport of multiprotocol data.

  • preboot execution environment (PXE)

    Preboot execution environment (PXE), pronounced pixie, is a set of standards that enables a computer to load an operating system (OS) over a network connection.

  • predictive dialer

    A predictive dialer is a telephone control system that automatically calls a list of telephone numbers in sequence, screening out no-answers, busy signals, answering machines and disconnected numbers while predicting at what point a human caller will be able to handle the next call.

  • presentation layer

    Residing at Layer 6 of the Open Systems Interconnection (OSI) communications model, the presentation layer ensures that the communications that pass through it are in the appropriate form for the recipient application.

  • private automatic branch exchange (PABX)

    A private automatic branch exchange (PABX) is an automatic telephone switching system within a private enterprise.

  • programmable network (PN)

    A programmable network is one in which the behavior of network devices and flow control is handled by software that operates independently from network hardware.

  • propagation delay

    Propagation delay is the amount of time required for a signal to be received after it has been sent; it is caused by the time it takes for the signal to travel through a medium.

  • PSTN (public switched telephone network)

    The public switched telephone network, or PSTN, is the world's collection of interconnected voice-oriented public telephone networks.

  • pulse code modulation (PCM)

    Pulse code modulation (PCM) is a digitalscheme for transmitting analogdata.

  • Q

    QAM (quadrature amplitude modulation)

    QAM (quadrature amplitude modulation) is a method of combining two amplitude modulation (AM) signals into a single channel.

  • R

    radio access network (RAN)

    A radio access network (RAN) is a major component of a wireless telecommunications system that connects individual devices to other parts of a network through a radio link.

  • radio frequency (RF, rf)

    Radio frequency (RF) is a measurement representing the oscillation rate of electromagnetic radiation spectrum, or electromagnetic radio waves, from frequencies ranging from 300 GHz to as low as 9 kHz.

  • Real-time Transport Protocol (RTP)

    Real-time Transport Protocol (RTP) is a network standard designed for transmitting audio or video data that is optimized for consistent delivery of live data.

  • registered port numbers

    The registered port numbers are the port numbers that companies and other users register with the Internet Corporation for Assigned Names and Numbers (ICANN) for use by the applications that communicate using the Internet's Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP).

  • repeater

    In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium.

  • Reverse Address Resolution Protocol (RARP)

    RARP (Reverse Address Resolution Protocol) is a protocol by which a physical machine in a local area network can request to learn its IP address from a gateway server's Address Resolution Protocol (ARP) table or cache.

  • reverse Telnet (direct Telnet)

    Reverse Telnet (sometimes called direct Telnet) is the initiation of a Telnet session from a computer system to one of its remote users.

  • rlogin (remote login)

    Rlogin (remote login) is a UNIX command that allows an authorized user to login to other UNIX machines (hosts) on a network and to interact as if the user were physically at the host computer.

  • ROADM (reconfigurable optical add-drop multiplexer)

    An ROADM (reconfigurable optical add-drop multiplexer) is a device that can add, block, pass or redirect modulated infrared (IR) and visible light beams of various wavelengths in a fiber optic network. ... (Continued)

  • round-trip time (RTT)

    Round-trip time (RTT), also called round-trip delay, is the time required for a signal pulse or packet to travel from a specific source to a specific destination and back again...(Continued)

  • route summarization (route aggregation)

    Route summarization, also called route aggregation, is a method of minimizing the number of routing tables in an IP (Internet Protocol) network. It works by consolidating selected multiple routes into a single route advertisement, in contrast to flat routing in which every routing table contains a unique entry for each route... (Continued)

  • router

    A router is a physical or virtual appliance that passes information between two or more packet-switched computer networks. A router inspects a given data packet's destination IP address, calculates the best way for it to reach its destination and then forwards it accordingly.

  • Routing Information Protocol (RIP)

    Routing Information Protocol (RIP) is a distance vector protocol that uses hop count as its primary metric.

  • routing table

    A routing table is a set of rules, often viewed in table format, that is used to determine where data packets traveling over an Internet Protocol (IP) network will be directed.

  • RS-232C

    RS-232C is a long-established standard ("C" is the current version) that describes the physical interface and protocol for relatively low-speed serial data communication between computers and related devices.

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